Hi Kelly: Maybe I should put it this way. As you accelerate on the dyno vacuum to the EGR valve starts at 1 HG at 10 MPH it goes to 2 Hg at 15 MPH it goes to 3 HG at 19 MPH it goes to 4 HG at 30 MPH. 6 HG or less is all you need for full EGR opening. And 3 inc... Login to read more.